Combustion oscillation in gas turbine combustor for fuel mixture of hydrogen and natural gas

研究成果: Conference contribution

3 被引用数 (Scopus)

抄録

Hydrogen as one of energy sources is attracting attentions because of CO2 free combustion that can deaccelerate global warming. Recently, hydrogen enriched combustion technology for gas turbine combustors is developing, in which hydrogen is added to natural gas. However, hydrogen-rich combustion has different combustion characteristics from conventional natural gas combustion. In particular, such variety of combustion characteristics may lead to combustion oscillation, which may cause fatigue breaking of structural elements due to resonance with components. Combustion oscillation is mainly induced by thermo-acoustics interaction. Therefore, it is necessary to investigate characteristics of hydrogen-enriched combustion sufficiently. To understand combustion characteristics of enriched hydrogen mixture, combustion experiments were performed for various ratios of hydrogen in the fuel mixture. In this study, a mock-up combustor of a micro gas turbine combustor is used, where a radial swirler is installed to mix fuel and air and stabilize the flame. To grasp the characteristics of combustion oscillation, pressure fluctuation was detected by a pressure sensor installed at the bottom of the combustor. It is found that larger hydrogen ratio in the fuel mixture extends the range of large pressure fluctuation region expressed by the root-mean-square value. Succeedingly, more detail oscillation characteristics were examined by FFT analysis. In the case of natural gas 100%, the oscillation of around 350 Hz was detected. On the other hand, in the case of the hydrogen-contained fuel mixture, two kinds of oscillating frequencies around 200 and 400 Hz were detected. To examine the cause of the difference among these three oscillating frequencies, a simplified stepped tube model with closed- and open-end is considered. For further investigation, acoustic boundary conditions were measured by acoustic impedance method. Moreover, to obtain the representative flame positions and temperature in the combustor, CFD calculations were performed, and the measured acoustic impedance was combined with the CFD results. Then, parametric studies with various thermo-pressure interaction index were performed to obtain the effect of thermo-pressure interaction index on natural frequencies and gains using the Nyquist plot. As a result, it was found that the self-excited oscillation limit is sensitive to the value of thermo-pressure interaction index.

本文言語English
ホスト出版物のタイトルFluid-Structure Interaction
出版社American Society of Mechanical Engineers (ASME)
ISBN(電子版)9780791857977
DOI
出版ステータスPublished - 2017
外部発表はい
イベントASME 2017 Pressure Vessels and Piping Conference, PVP 2017 - Waikoloa, United States
継続期間: 2017 7月 162017 7月 20

出版物シリーズ

名前American Society of Mechanical Engineers, Pressure Vessels and Piping Division (Publication) PVP
4
ISSN(印刷版)0277-027X

Other

OtherASME 2017 Pressure Vessels and Piping Conference, PVP 2017
国/地域United States
CityWaikoloa
Period17/7/1617/7/20

ASJC Scopus subject areas

  • 機械工学

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